In accordance with the performance improvement, such as enhanced functionality and density, of information communication devices in recent years, printed wiring boards are also required to have performance responsible thereto. A hardened material of a thermoset resin composition is used as an insulating material that forms a printed wiring board. Among thermoset resin compositions, an epoxy-based resin composition that contains an epoxy-based compound is widely used in view of the cost and adhesiveness. In particular, multilayer wiring boards are recently developed to correspond to the reduced thickness and size and enhanced performance of electronic devices.
JP5120520B describes using, for example, an active ester resin as the hardening agent for such an epoxy-based resin composition. It is said that, by using the ester resin as disclosed in this patent literature, a thermoset resin composition having both excellent heat resistance and flame retardance can be obtained while the hardened material has low permittivity and low dielectric tangent.
JP5120520B describes that the above ester resin is generated by reacting a phenolic hydroxyl group-containing substance and aromatic dicarboxylic acid or aromatic dicarboxylic acid chloride.
JP2014-62243A, on the other hand, describes an aromatic vinylbenzyl ether compound that gives a hardened material having excellent dielectric characteristics (low permittivity/low dielectric tangent) even after moisture absorption under a high-temperature and high-humidity environment and also having a high glass-transition temperature and flame retardance.